Improving alternative fuel utilization: detailed kinetic ......Chemical kinetic model chemical...

Lawrence Livermore National Laboratory

Improving alternative fuel utilization: detailed kinetic combustion modeling & experimental testing

Salvador Aceves, Daniel Flowers, Bill Pitz, Charlie Westbrook, Emma Silke, Olivier Herbinet, Lee Davisson, Bruce Buchholz, Nick Killingsworth

DOE National Laboratory Alternative Fuels R&D Merit Review and Peer Evaluation

Washington, DCThis presentation does not contain any proprietary or confidential information

This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

Goals/Objectives: Enable efficient utilization of alternative fuelsthrough detailed chemical kinetic and fluid mechanics analysis

H3C

C CH3

H2C

H3C

CH

CH2O

.O

H2C

C CH3

H2C

H3C

CH

H3C

O

HOH3C

CH

H2C

H3CCH

H2C

OO.

O

OH

Additive 1

Additive 2

Additive 3

Additive 4

H2C

C CH3

H2C

H3C

CH2

O

O.

O

HO

H2C

C CH3

H2C

H3C

C

H3C

O

HO

O

CH3 O.

Additive 5

H3C

CH C

H3CCH2

Additive 122

O

O

OH

HC

O

O

HO

Additive 103

O

OHO

O.

H3C

C CH3

H2C

H3C

C

H3CO

CH3 OH

Additive 204

0

20

40

60

80

100

120

140

160

180

200

650 700 750 800 850 900

Compressed Temperature / K

_ / m

sτ

High fidelity engine analysis and

Chemical kinetic model chemical kinetic model testing at

high stratification

no stratification

medium stratification

40

50

60

70

80

90

100

-10 -5 0 5 10 15 20crank angle, degrees

pre

ssu

re, b

ar

ExperimentalMulti-zoneNeural network

2Option:UCRL# Option:Additional Information


development and validation engine conditions

FY2007 Reviewer’s Comments and Response

Understand if indeed methyl decanoate is a representative surrogate for biodiesel. Another project indicated deficiencies.Our work has demonstrated good agreement betweennumerical results for methyl decanoate and experimental results for rapeseed oil

Can the combustion kinetic modeling be combined with flowreactor studies to get better validation data and a deeperunderstanding? Much of our validation is conducted at flow reactor conditions.

Some of the tasks and data were also presented in thecombustion session. There is overlap between the “Combustion” and the “Alternative Fuels” part of our work. Weminimize overlap in the presentations by clearly distinguishingresults most relevant to the combustion session from those most relevant to the alternative fuels session.



FCVT Barriers: our work is sharply focused on addressingtechnical barriers that limit applicability of alternative fuels

Inadequate data and predictive tools for property effects on combustion and engine optimization: Our detailed models

enable high fidelity analysis for engine optimization

Inadequate data and predictive tools for fuel effects on emissions and emission control system impacts: Our high

fidelity chemical kinetic models are applicable to emissions

predictions (HC, CO, NOx and PM) in HCCI and other low

temperature combustion regimes

Inadequate knowledge base on the technical and economic impacts of non-petroleum fuels: Our analysis tools enable

clean and efficient utilization of alternative fuels such as

biodiesel



Approach: We are developing high fidelity surrogate modelsthrough testing and tuning with our innovative engine analysis codes

5.88 mm

(0.2314 in)

5.23 mm

(0.206 in)

9.01 mm

(0.355 in)

0.305 mm

(0.0120 in)

102 mm

(4.02 in)

testing

tuning

Detailed kinetics of High fidelity



gasoline surrogates engine models

Technical accomplishment summary: developing high fidelity surrogatechemical kinetic models for practical fuels (diesel, gasoline, biodiesel)

Surrogate fuel palette for gasoline

cyclohexane

methylcyclohexane

iso-pentanes

iso-hexanes

iso-octane

toluene

Xylene

pentenes

hexenes

CH3

n-butane n-pentanen-hexane n-heptane

CH3

Our gasoline surrogate model includes

n-alkane branched alkane olefins cycloalkanes aromatics


Lawrence Livermore National Laboratory detailed mechanisms for all the chemical classes

We have proposed and tested three gasoline surrogate mechanisms



Mixture 1: average gasoline

composition

Mixture 2: similar octane

number as gasoline

Mixture 3: enhanced reactivity

We have recruited LLNL’s analytical chemistry groupfor detailed evaluation of small hydrocarbon species in HCCI exhaust

Tedlar bags

Purge and Trap Gas chromatographymass spectrometer (GC-MS)

Sandia Engine



Our innovative numerical techniques have enabled fast, high fidelity



-30 -20 -10 0 10 20 30

crank angle, degrees.

2000

3000

4000

5000

6000

7000

8000

9000P

ress

ure,

kP

a.

!=0.26

!=0.24

!=0.22

!=0.20

!=0.18

!=0.16

!=0.12

!=0.08

!=0.04

!=0.10

!=0.14

!=0.06

Solid lines: experimentalDashed lines: numerical

analysis of homogeneous and partially stratified combustion

5.88 mm

(0.2314 in)

5.23 mm

(0.206 in)

9.01 mm

(0.355 in)

0.305 mm

(0.0120 in)

102 mm

(4.02 in)

Unprecedented level of agreement obtained between

experimental (Sandia) and numerical (LLNL) results

We have demonstrated unprecedented modeling fidelityaccurately predicting exhaust composition of 50 species

10 Option:UCRL# Option:Additional Information


Isooctane Formaldehyde 2-Methyl-1-propene

Acetone Methane Ethene

We are combining our chemical kinetics codes, engine models, andanalytical chemistry to deliver high fidelity surrogate models



High quality HCCI

engine experiments

(Sandia)

Analytical chemistry for

detailed exhaust speciation

Extensively validated

chemical kinetic models

High fidelity engine analysis


We have conducted detailed speciation experimentsat Sandia HCCI engine with Chevron-Phillips reference gasoline

• Conducted both phi-sweep and

stratified charge experiments

• 18 samples collected in triplicate

• Emission bench and detailed species in

good agreement

• 70 individual exhaust species

identified and quantified

• 11 different authentic standards used

for quantification

• >1000 individual analyses reported

Option:UCRL# Option:Additional Information 12

We are developing chemical kinetic mechanisms forrepresentative & surrogate diesel/biodiesel species

N-hexadecane

• Diesel primary reference fuel

• Representative of diesel fuel

O

O

2,2,4,4,6,8,8 heptamethylnonane

• Diesel primary reference fuel

methyldecanoate

• Biodiesel surogate



n-Hexadecane model agrees well with experimentsand it is ready for detailed diesel engine analysis



In stirred reactor at 1 atm and 1000-1250K

Curves: Model

Symbols: Ristori et al. 2001

Biodiesel surrogate methyl decanoate accurately predictsignition chemistry relative to rapeseed oil combustion

Experiment: Rapeseed methyl esters



1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

790 840 890 940 990 1040

Temperature (K)

Mol

e Fr

actio

n

O2 CO2 CO CH4 C2H4

methyl decanoate

O

O

Biodiesel fuels contribute to lower HC, CO and PM emissions,but increase the level of NO emissionsx



Source: NREL

Is there a chemical reason for the increase in NO with biodiesel?x

25-50%

5-10%

2-5%

20-40% 20-40%

50-70%

15-40% 0-5%

Main species in biodiesel Representative molecules in

diesel fuel (Farrell et al., 2007)



Conclusion: biodiesel burns hotter because it has multiple double bondsHotter burn increases NOx



Technical Publications during FY08 C. K. Westbrook, W. J. Pitz, O. Herbinet, H. J. Curran and E. J. Silke, "A Detailed Chemical Kinetic Reaction Mechanism For n-

Alkane Hydrocarbons From n-Octane to n-Hexadecane," Combust. Flame (2008) Submitted.

E. J. Silke, W. J. Pitz, C. K. Westbrook, M. Sjöberg and J. E. Dec, “Understanding the Chemical Effects of Increased Boost Pressure under HCCI Conditions”, 2008 SAE World Congress, Detroit, MI, SAE 2008-01-0019, 2008.

R. P. Hessel, D. E. Foster, S. M. Aceves, M. L. Davisson, F. Espinosa-Loza, D. L. Flowers, W. J. Pitz, J. E. Dec, M. Sjöberg and A. Babajimopoulos, Modeling Iso-octane HCCI using CFD with Multi-Zone Detailed Chemistry; Comparison to Detailed Speciation Data over a Range of Lean Equivalence Ratios, SAE 2008-01-0047, 2008.

Sakai, Y., Ozawa, H., Ogura, T., Miyoshi, A., Koshi, M. and Pitz, W. J., "Effects of Toluene Addition to the Primary Reference Fuel at High Temperature," SAE Commercial Vehicle Engineering Congress & Exhibition, Chicago, IL, 2007.

Y. Sakai, A. Miyoshi, M. Koshi and W. J. Pitz, “A Kinetic Modeling Study on the Oxidation of Primary Reference Fuel–Toluene Mixtures Including Cross Reactions between Aromatics and Aliphatics”, Proc. Combust. Inst., Montreal, Canada, submitted, 2008.

K. Seshadri, T. Lu, O. Herbinet, S. Humer, U. Niemann, W. J. Pitz and C. K. Law, "Ignition of Methyl Decanoate in Laminar Nonpremixed Flows," Proceedings of The Combustion Institute (2008) Submitted.

C. K. Westbrook, W. J. Pitz, P. R. Westmoreland, F. L. Dryer, M. Chaos, P. Osswald, K. Kohse-Hoinghaus, T. A. Cool, J. Wang, B. Yang, N. Hansen and T. Kasper, “A Detailed Chemical Kinetic Reaction Mechanism for Oxidation of Four Small Alkyl Esters in Laminar Premixed Flames”, Proc. Combust. Inst., Montreal, Canada, submitted, 2008.

Joel Martinez-Frias, Salvador M. Aceves, Daniel L. Flowers, “Improving Ethanol Life Cycle Energy Efficiency by Direct Utilization of Wet Ethanol in HCCI Engines,” Journal of Energy Resources Technology, Vol. Vol. 129, No. 4, pp. 332-337, 2007.

George A. Ban-Weiss, J.Y. Chen, Bruce A. Buchholz, Robert W. Dibble, “A Numerical Investigation into the Anomalous Slight NOx Increase when Burning Biodiesel: A New (Old) Theory,” Fuel Processing Technology, Vol. 88, pp. 659-667, 2007.



Collaboration: We have long standing partnershipswith industry, national labs, and academia

Industry Partners: • Collaborative modeling and analysis of experiments

National Labs and Universities: • Modeling tools, experiments, analysis



Other collaborative activities Ongoing participation at MOU meetings with vehicle and engine

manufacturers

Fuels for Advanced Combustion Engines (FACE) working group

Surrogate fuel working group with representatives from industry (Exxon,Caterpillar, Chevron, United Technologies)

Basic Energy Sciences panel on advanced combustion

SAE HCCI symposium, Lund, Sweden, 2 invited seminars

Chalmers University, Opponent in Ph.D. exam

8 PhD and >15 MS through collaboration and direct support

Several collaborative publications involving National Laboratoriesand Universities in the US and abroad:

• SAE

• The Combustion Institute

• International Journal of Engine Research

• Combustion Theory and Modeling

• Journal of Energy Resources Technologies

• IEEE Control Systems Technology



Future plans: We will deliver high fidelity surrogate modelsfor gasoline and diesel fuels

n-hexadecane

2,2,4,4,6,8,8 heptamethylnonane

O

O

methyldecanoate

gasoline surrogate diesel/biodiesel surrogate



Summary: We are combining our chemical kinetics codes, engine models,and analytical chemistry to deliver high fidelity surrogate models

Detailed chemical kinetics

testing

tuning

High fidelity

5.88 mm

(0.2314 in)

5.23 mm

(0.206 in)

9.01 mm

(0.355 in)

0.305 mm

(0.0120 in)

102 mm

(4.02 in)



engine models

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